Modern tire changing equipment today ranges from a variety of simple, manually-operated systems to complex, automated, pneumatically-driven systems. The extremely high cost and technical skill required to operate the equipment makes many of the automated systems prohibitive for certain users, particularly low volume users or those dealing with specialty tires. Manually-operated equipment, therefore, is still pervasive throughout the tire changing equipment market, providing affordable tools that can be adapted to a variety of work environments. Unfortunately, many tire changing apparatus, both automated and manually-operated, are not particularly suited for use with a wide range of tire sizes and/or wheel rim types.
There are essentially two types of manually-operated tire mounting and demounting apparatus in use today. One type of tire changer employs a rim clamping device or system to securely hold the rim stationary while mounting or demounting the tire. For example, Thostenson U.S. Pat. No. 2,873,777 discloses a center post tire changing apparatus with a wheel mount comprising radial arms which grip and clamp a rim circumferentially. The radial clamps extend and retract to accommodate rims of different, but limited, diameter. U.S. Pat. Nos. 2,534,515, 2,888,064, and 1,538,875 disclose similar rim clamping devices. Disadvantageously, however, all of these rim clamping devices or apparatus require significant clamping force be applied to the wheel rims in order to secure the wheel to the apparatus and prevent rotation of the wheel during the mounting or demounting operations. Oftentimes, the amount of clamping force may be excessive, thereby causing wheel deformation or damage to the rim of the wheel, particularly where small, lighter (e.g., aluminum) wheels are employed.
Accordingly, in order to prevent rim deformation, the other common type of tire changing apparatus is often employed. This type of manually-operated tire changing apparatus includes a center post over which the wheel in placed, and an adapter, spacer or other clamping device or assembly is then threaded or otherwise secured to the center post and secures the wheel near its center. In order to prevent rotation, the other side of the wheel may be pinned against a plate near its center or may rest on its rim. However, placement of the tire on the rim, like the rim clamping devices, often leads to damaged or deformed rims. Moreover, use of a plate might also deform or damage the wheel near its center.
Consequently, in order to avoid the potential for wheel deformation, a pin blocking mechanism has been developed in the prior art. Generally, such a mechanism includes additional parts such as bolts that may be placed through the lug holes of the wheel and through corresponding holes in the plates or adapters located on the apparatus in order to securely hold the wheel in place. For example, Johnson U.S. Pat. No. 3,867,975 teaches a floor-mounted, center-post tire changing tool with a threaded center bar for use on small wheels in the 4 to 12-inch diameter range. The wheel is secured from rotation on the tire changer by inserting bolts through the wheel's lugholes matched to holes on a plate concentric with the post. U.S. Pat. Nos. 3,065,449 and 3,717,192 also disclose various pin blocking mechanisms. Further, Beemer U.S. Pat. No. 4,461,335 teaches a center post tire changer with a baseplate through which a pin can be inserted to prevent wheel rotation. The pin block works in conjunction with a curved rim engaging flange which exerts axial force on the wheel center hole to center the wheel and prevent rotation. Foster U.S. Pat. No. 3,056,449 similarly discloses a conical flange to exert axial force on the wheel center hole.
While the use of pin blocking mechanisms avoids the potential for wheel deformation inherent with rim clamping and the like, there are clear disadvantages to using an apparatus limited to only this means of wheel rotation prevention. In some instances, certain prior art center-post tire changing apparatus are limited for use on wheels having only a particular lug pattern. In other words, the range of wheel types and sizes that can be mounted may be limited due to a mismatch between the lug pattern of the wheel and the pin holes on the tire changer. However, at least one patent, Garthe U.S. Pat. No. 3,211,206, has developed an adapter plate to accommodate various lug patterns on a center-post tire changer.
This patent notwithstanding, pin blocking systems are necessarily dependent upon the wheel having lugholes, thus limiting the types of wheels the tire changer can accept. Desirably, a manually-operated tire mounting and demounting apparatus should have the capability of mounting or demounting tires from all types of wheels, including straight wheels (i.e., wheels having a single centering hole for the axle and no lugholes), bearing wheels (i.e., wheels similar to straight wheels but having an inner bearing race located in the centering hole), lug wheels (i.e., wheels having a center hole and lugholes as commonly found on automobiles), and ATV wheels (i.e., wheels, with or without lugholes, having a deep center or high rims extending well above the center portion of the wheel, also known as deep dish-type wheels). To date, the art has not provided a center-post tire changing apparatus that can be used to change tires on all of these types of wheels. The need, therefore, exists for a center-post tire changer that can be used to change tires on all types of wheels.
Once the wheel is securely mounted on the center-post tire changing apparatus, a tire iron or similar device may be used to pry the bead of the tire over the rim. The tire iron or a similar device may also be used for remounting the tire over the wheel rim. The advantage of the center post tire changing apparatus is that the tire mounting and demounting actions often utilize the center post as a fulcrum to apply the necessary force to the tire iron to lift the bead of the tire over the wheel rim.
In order to change a tire, it is first necessary to detach or "break" the bead of the tire away from the rim at the periphery of the wheel. In some cases this can be very difficult and, oftentimes, a device known as a bead breaker is required to aid in the performance of this task. Since breaking the bead is often a part of changing a tire, it is believed desirable to include a bead breaker with the tire mounting or demounting apparatus. Such bead breakers are desirably either permanently or temporarily attached to the tire changing apparatus.
The prior art has developed several types of bead breakers, some of which are lever actuated. Common to these is a bead-engaging foot pivot-mounted medially between the lever arm ends. Less common, but also known, is one end of the lever arm mounted adjustably with respect to the horizontal distance from the lever mount to the radial plane of the tire mounted for bead breaking. These features generally allow for accommodation of a range of tire diameters and widths in the bead breaker. However, the prior art disclosures vary in the means of mounting the lever and the location of the lever mount relative to the tire mounted for tire removal. These variations directly impact the operational complexity of the bead breakers.
Larson U.S. Pat. No. 2,602,494 teaches a lever actuated bead breaker mounted horizontally above the tire. The lever arm is pin-mounted to a side post, with the horizontal position of the lever mount adjustable by changing the pin position in any of several holes disposed along the axis of the post. This configuration requires the user to manually adjust pin position and to release the tire from a mounting bracket and then turn over the tire to break the other bead. Hence, the tire must necessarily be resecured in a mounting bracket twice during the beak breaking process.
Thostenson U.S. Pat. No. 2,873,777 teaches a center-post tire changer with lever actuated bead breakers mounted on the post. A lever arm extension is interchangeable in removable slide-mounted brackets above and below the tire mount on the tire changing apparatus. The horizontal positions of the lever mounts above and below the tire are continuously adjustable by sliding the mounts along the post axis. Thus the tire is mounted only once for bead breaking but remounting of the lever arm extension is required for each bead breaking. Moreover, it is well known that it is sometimes very difficult to break a bead of a tire from a wheel rim from below the tire.
Beemer U.S. Pat. No. 4,461,335 teaches a center-post tire changer with a lever-actuated bead breaker slide-mounted on the post above the tire mount. The tire must be mounted twice during bead breaking. The lever arm also serves as the tire iron so the bead breaker must be disassembled before tire dismounting and mounting and reassembled for the next tire.
The prior art thus discloses in various forms adjustable bead breakers that accommodate a range of tire widths and diameters. The prior art does not, however, disclose a continuously adjustable bead breaker permanently mounted on a center post tire changer that allows for breaking both beads of a tire without remounting the tire on a bracket before breaking the second bead. A need exists, therefore, for a center post tire changer with such a bead breaker.